I was doing research on this topic and was shopping around to get this done and some other preventive maintenance on the car since I got it 3 weeks ago. I'm not familiar with the walnut cleaning vs chemical cleaning. I spoke to a shop here in Miami, very nice and friendly Eurowerks and they do a 3 step process with a product BG Cleaning. I wanted to see if this is actually something worth spending my money on aside from an Oil change. My car currently has 88k and its an 07. The idle is not bad at all but just want to prevent anything bad from happening. I was quoted $280 for the 3 step process and $100 for the oil change. I need some input since I'm taking the car in on Saturday. Thanks in advance,